Electrical connector



April 7, 1970 c. A. DAMM AlT AL ELECTRICAL CONNECTOR Filed April a. 1968 INVENTUM CARL DAMM ALBE c. ElcHMANN w|| Mum PRN- BY l v v 1| Ilw AVI- L ON l u 4 a A T TORNE YS United States Patent Otiice 3,504,592 Patented Apr. 7, 1970 U.S. Cl. 89-1 14 Claims ABSTRACT F THE DISCLOSURE An electrical connector including a llexible armored sheath having an insulated conductor threaded therethrough an electrically connected between a plug unit and a breech cap which is adapted for applying a ring signal to a pyrotechnic cartridge and which has ilanged spring pins formed to function both as ground contacts and as spent cartridge extracting means. A braided sheath encircles the armored sheath and is mechanically connected at one end to the breech cap and at the other end through a turnbuckle-like sheath stretching assembly to the plug unit. The stretching assembly enables the braided sheath to be longitudinally stretched so that it tightly grips the armored sheath yand forms therewith a more rigid conduit.

STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Pyrotechnically actuated bomb racks are frequently rendered inoperable by reason of the electrical failure of a connector which terminates at one end in a breech cap adapted for applying a detonation signal to a pyrotechnic cartridge carried in an ejector assembly. The connector needs to be llexible and cannot be secured to adjacent structure of the bomb rack because the breech cap must be removed to load cartridges. Flexible connectors are subjected to butleting by air turbulence during flight which causes the connector to vibrate with consequential weakening and eventual severance of the electrical conduction path.

SUMMARY OF THE INVENTION It is the general purpose of this invention to provide an improved electrical connector which assures that a good electrical conduction path will be maintained and which can be made still enough to resist the deleterious effects of buffering by air turbulence and yet does not interfere with easy disconnection of the breech cap from its associated pyrotechnic ejector assembly. Briefly, this is accomplished by providing a flexible armored sheath through which extends an untensioned length of conductor electrically interconnecting the breech cap and an anchor and plug unit; by providing a stretchable sheath which encases the flexible armored sheath and is mecanically connected in a linkage between the breech cap and the anchor unit; and by providing adjustable stretching devices, such as a breech cap coupling or an assembly interconnected between an end of the stretchable sheath and the cap or the anchor unit, for longitudinally stretching the encasing sheath and causing it to grip the periphery of the armored sheath and form a more rigid conduit which can withstand intense air turbulence. Additionally, the invention further contemplates that a good electrical conduction path to the pyrotechnic cartridge be maintained by providing ground contact pins of an improved design, The ends of the tubular pins are obliquely cut to facilitate piercing and gripping the cartridge casing when the breech cap has been coupled in operative position to the associated ejector assembly cartridge chamber and to facilitate extracting the spent cartridge.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 represents a side View partially in cross section of a connector according to the invention;

FIG. 2 represents an enlarged view in longitudinal cross section of a portion of a llexible armored sheath included in the connector of FIG. l;

FIG. 3 represents an enlarged side View of a disengaged ground contact pin including in the connector of FIG. 1;

FIG. 4 represents an end view of the pointed end of the pin of FIG. 3; and

FIG. 5 represents an enlarged cross-sectional view of the pin in piercing engagement with a cartridge casing.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. l, the connector 10 terminates at one end in a breech cap 11 generally of the type described in U.S. patent application Ser. No. 700,603, tiled Jan. 25, 1968, by Carl A. Damm for Breech Cap for Applying Signals to Explosive Cartridges. The breech cap 11 includes a rotatable, inwardly flange coupling 12 which is connected to a barrel 13 of an ejector assembly (not shown) such as that generally described in U.S. Patent No. 3,036,852 to C. W. Mullison, issued May 29, 1962, and in U.S. patent application, Ser. No 657,738, tiled July 3l, 1967, by Carl A. Damm for Ejector Assembly with Lockable Store-Engaging Pressor Foot now U.S. Patent No. 3,431,824 issued Mar. 1l, 1969. The breech cap further includes an apertured breech closing plate 14 through which protrude force lit, llanged ground contact pins 15, hereinafter more fully described, and a spring-loaded primary contact 16. The pins 15 and 16 establish good electrical contact with a pyrotechnic cartridge 17 which is received Within the barrel 13 and is of the type detonated by an electrical firing signal. The tubular coupling 12 may include a plurality of key slots (not shown) longitudinally extending from the barrel adjacent end of the coupling 12 and sized to receive a spring loaded key (not shown) for preventing relative rotation of the coupling 12 and the barrel 13.

The breech cap 11 also includes a flanged, stainless steel pressure dorne 18 which is welded to and closed by the plate 14 and which, among other things, sandwiches the ground Contact pins 15 in position. The rotatable coupling 12 is retained adjacent the flanged end of the dome 18 by a metal snap ring 12a seated in a peripheral groove formed in the dome l8r. A flexible, insulated conductor 19 which extends into the dome 18 has a stranded signal lead (not shown) electrically connected at one end with the primary Contact 15 and has an inner ensheathing, braided ground shield (not shown) insulated from the lead and mechanically and electrically connected to the dome 18. The other end of the conductor 19 extends into a hollow anchor unit 20 and is electrically connected to a plug 21 which protrudes from the anchor unit 20. The anchor unit 20 is rigidly connected as by bolts (not shown) with a framing structure 22 rigidly connected to the bomb rack after insertion of the plug 21 into an aperture 22a formed in the structure 22 for establishing an electrical connection with a recessed receptacle 23 mounted in the aperture 22a. The receptacle 23 is electrically connected with a control unit (not shown) which provides the electrical tiring signal to be applied by the cap 11 to the cartridge 17.

The conductor 19 extends through an aperture formed in the end of the dome 18 remote from the barrel 13 and is threaded through a tubular boss 30 which fixed to and protrudes from the dome 18. The extended end of the boss 30 terminates in a radially extending `iiange '31 and has a coaxial bore 30a extending thereinto which is sized to slidingly receive an end of a dlexible armored sheath 32 through which the conductor 19 is threaded. The other end of sheath 32 is slidingly received by a turnbucklealike stretching assembly 40 through which the conductor 19 is threaded.

The stretching assembly 40 includes a coaxially apertured, internally threaded adjusting bolt 41 Which has a hexagonal head and oppositely directed, similarly pitched, external threads and which is threadably engaged by the anchor unit 20. One end of a coaxially apertured ditting 42 is threaded into the bolt 41. The other end of the fitting 42 terminates in a anged boss `43 having a coaxial bore 43a extending thereinto which is sized to slidingly receive the other end of the armored sheath 32. The medial portion of the fitting 42 includes a radially projecting, locking llange 44. The fitting 4.2, the adjusting bolt 41 and the anchor unit 20 are so interconnected that threading the bolt 41 into the anchor unit 20 causes the :fitting 42 and its boss 43 to be drawn toward the anchor unit 20.

It is preferred that the conductor 19 not be tensioned. By loosely threading the conductor 19 through the armored sheath 32 and forming a loop or bend 19a therein within the cavity of the anchor unit 20, a connector configuration is established wherein little vibration is transmitted to the conductor lead which could eventually cause an electrical failure.

A tubular braided :sheath 50 of stainless steel having a plurality of double-stranded interwoven helical coils 51 is rmly connected at its ends to the bosses 30 and 43 of the cap 11 and the fitting 42 of the stretching assembly 40 as by swaged sleeves 52 and 53. While the braided sheath 50 may be joined to the boss 30 0f the cap 11 by any desired method, the preferred embodiment includes a thin polyurethane sheath 54 which extends along the periphery of the boss 30 and which provides a seat into which the strands 51 of the braided Sheath 50, which have been bent over the ilange 31, may be imbedded by the swaged sleeve 52. Another desirable method (not shown) of swaging the braided sheath 50 to the boss 43 of the stretching assembly 40 contemplates the use of a pair of swaged sleeves made of materials having differing shrink rates so that the inner sleeve made of a material such as plastic is swaged directly to the boss 43 and provides the seat into which the strands 51 may be imbedded by the overlying swaging sleeve.

The length of the braided sheath 50 relative to the length of the armored sheath 32 is chosen so that in the particular installation the substantially untensioned sheath 50 assumes the greater diametered profile, generally indicated in exaggeration by dotted lines in FIG. 1, when the coupling 12 is unthreaded or the assembly 40 is adjusted to have its greatest integral length. For installing the connector in a particular rack, the assembly 4|] is adapted for a suflicient initial reduction in length when the cap 11 has been firmly seated against the cartridge 17 so that the braided sheath 50 can be longitudinally stretched and reduced in diameter so that the helical strands 51 are stretched and tensioned to iirmly grip the underlying periphery of the armored sheath 32 and form therewith a conduit of desired rigidity. The boss 43 is long enough so that the end of the armored sheath 32 remains within the bore 43a after the assembly 40 has been shortened to cause the braided sheath 50 to be necked down for tightly gripping the underlying armored sheath 32. Thereby, a substantially rigid conduit may be formed which can withstand the buieting effects of air turbulence. At any time thereafter, the stiffness of the conduit may be relaxed by loosening the coupling 12 to untension the braided sheath 50. When the breech cap 11 is disconnected from the barrel 13, the armored sheath 32 may be flexed or bent to facilitate extracting the spent cartridge 17 and loading another cartridge 17. Further adjustment of the assembly 40 is usually unnecessary unless the coupling 12 is unable to sufficiently :stretch the sheath 50.

Referring to FIG. 2, the armored sheath 32 is formed from a helically coiled strip 61 having an inwardly depending tongue 62. which interlocks with a trough 63 inwardly depending from the confronting edge of the adjacent turn of the strip 61. Since the strands 51 of the braided sheath 50 tightly grip the periphery of the coiled strip 61 when the stretching assembly 40 has been tightened, tlexure or bending of the connector 10 is inhibited. Also, when the braided sheath 50 is stretched to radially compress the armored sheath 32, the tongue `62 tends to more closely engage the trough 63 and resist longitudinal sliding movement characteristically present when the armored sheath 32 is bent. The armored sheathy 32 also includes a flexible plastic liner 64 which facilitates conductor insertion and protects the conductor 19 from damage by the sheath 32.

Referring again to FIG. l, the head of the adjusting bolt -41 has a plurality of longitudinal slots such as 41a formed therein, any one of which may be longitudinally registered with keying slots 20a and 44a formed in the anchor unit 20 and the locking flange 44 of the fitting 42. An elongated key 70 is held in locking position by a pair of bifurcated spring clips 71 and 72 spaced to be arranged on opposite sides of the head of the bolt 41 for clipping engagement of the shanks of the fitting 42 and the bolt 41. The key 70 is positioned to prevent rotation of the adjusting bolt 41 once the desired degree of the longitudinal stretching of the braided Sheath 50 has been imposed. A snap-on plastic cover functions to streamline the connector configuration, reducing the causation of turbulence, and to protect the stretching assembly 40 from the accumulation of dirt and ice which could impair its operation.

Referring to FIG. 3, the stainless steel ground contact pins 15 aremfabricated from flanged, cylindrical spring pins made jof about two .turns of spirally wound rectangles of spring steel. As shown in FIG. 4, the piercing point 91 of the pin 15 has been formed by obliquely truncating a cylindrical pin as by cutting or grinding to form an elliptical pin terminus lying in a plane extending obliquely of the longitudinal axis A of the pin 15. It has been found that, as shown in FIG. 5, when the pin 15 is being forced into the aluminum casing of the cartridge 17 by threading the coupling 12 onto the barrel 13 to seat the plate 14 against the cartridge 17, the laminated walls of the pin point 91 tend to slightly diverge outwardly of the pin axis A and be forced obliquely into the aluminum casing. The furthest projecting portion of the point 91 is deflected outwardly the greatest degree. The

above-described pin configuration not only provides any excellent electrical contact with the cartridge 17 but also facilitates spent cartridge extraction in that, as the uncoupled breech cap 11 is withdrawn from operative position, the points of the pins 15 tend to continue to grip the cartridge 17 and extract it from the barrel 13.

Several factors inuence the design of the pins 15. For example, it has been discovered that the distance that the points of the stainless steel spring pins 15 project beyond the plate 14 should be about eighteen-thousandths of an inch when three ground contact pins having one-sixteenth inch diameters are to pierce an aluminum cartridge casing. Longer point projections prevent complete pin penetration and leave a gap between the plate 14 and the cartridge which can cause the pins 15 to be subjected upon detonation to suflicient cartridge kickback to stress the pins 15 beyond their elastic limits and impair the reuse of the cap 11 and connector 10. It has been found that when the projecting ends of the pins 15 are too blunt,l

e.g., define a plane substantially normal to the pin axis, the pins will not pierce the aluminum cartridge casing a suflicient degree for gripping engagement. On the other hand, if the points 91 are too sharp, eg., in the above specific example, define a plane which is about 30 oblique to the pin axis A, seating the cap 11 on the barrel 13 and tightening the coupling 12 causes the material in the points 91 to be stressed beyond its elastic limit, thereby causing pin point splaying and impairing reuse of the connector 10. While 45 points usually have been found to be satisfactory for three one-sixteenth inch diametered pins used to pierce aluminum, a more blunt point such as one defining a plane which is about 60 oblique to the pin axis A is preferred in order to maintain a good electrical conduction path and to assure the feature of ability to extract spent luminum cartridges. When the spent cartridge 17 is disengaged from the pins 15, the pin points 91 spring back to their normal orientation and are ready for reuse.

Another factor to be considered in designing reusable pins 15 is the peripheral location along the point 91 of the projected end of the outer longitudinally extending wound rectangle edge 92. When the end of the edge 92 lies along the furthermost projecting half of the point 91, the pin point material tends to be stressed beyond its elastic limit upon being forced into a cartridge casing and, consequently, tends to be permanently deformed. Permanent pin point splaying can be avoided by locating the edge 92 in the other half of the pin 15 which projects the least. Thus, the portion of the point 91 being forced into the casing which will undergo the greatest deflection from the longitudinal axis generally maintains the cross-sectional configuration of an unbroken double-layered elliptical arch during the piercing process. Since the material of the portion being inserted is more uniformly stressed, point deformation within the elastic limits of the material is better assured.

It is preferred that the edge 92 be peripherally located halfway between the longitudinal locations of the greatest and least point projection, i.e., that the length of the edge 92 be equal to the average length of the pin. This configuration facilitates mass production of the pins 15 by enabling the use of a pair of jigs having at one end contiguous, coplanar edges slanted at the desired angle for the points 91 and having a plurality of opposed semicylindrical bores extending normal to the slanted edge for receiving a plurality of unfinished pins 15. The edges 92 of the pins 15 may be easily indexed into alignment with the longitudinal boundaries of the bores in one of the jigs prior to positioning the mating jig. The proper peripheral location of the edge 92 is thereby assured for each pin 15.

The invention provides an electrical connector of greatly improved design which vastly increases the reliability of the bomb rack in that a good electrical connection between the cartridge 17 and the signal source via the receptacle 23 is continually assured. Vibration incident to in-flight conditions does not tend to cause failure of the electrical interconnection between the cartridge 17 and the signal source in that the ground contact pins engage or grip the cartridge casing with spring-like action and in that the conductor 19 does not tend to vibrate and remains in an untensioned state, preserving the conduction path to the primary and ground contacts 15 and 16. The flexible armored sheath 32 and the tensioned braided sheath 50 coact to form a substantially rigid conduit through which the conductor 19 is loosely threaded. The relaxable conduit formed thereby resists buifeting and vibration stimulated by air turbulence which could cause severance of the conductor 19 or other failure of the connector 10.

It is contemplated, of course, that other known plug configurations not shown should be utilized. For example, the plug 32 could be mounted on the end of a conduit rigidly secured to the frame which threadably receives a coupling member connected to the plug 21. It

is further contemplated that the connector 10 could include thermal insulation liners extending along the length of the armored sheath 32 for preventing possible melting of the shield and lead of the conductor 19 in the presence of rocket blasts.

It should be understood, of course, that the foregoing disclosure relates only to a preferred embodiment of the invention and that numerous modifications or alterations may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. A connector comprising:

first and second connecting means;

a flexible sheath extending between said first and said second connecting means;

a tubular stretchable sheath having said flexible sheath threaded therethrough and having one of its ends mechanically connected to one of said first and second connecting means, said stretchable sheath having a diameter `which varies as a function of elongation; and

adjustable stretching means mechanically interconnected between said stretchable sheath and the other of said first and second connecting means for elongating said stretchable sheath relative to said flexible sheath a sufficient degree to enable said stretchable sheath t0 peripherally grip said flexible sheath.

2. A connector according to claim 1 wherein:

said stretchable sheath comprises a plurality of helically coiled strands interwoven to form a longitudinally stretchable tubular sheath.

3. A connector according to claim 2 wherein:

said flexible sheath comprises a helcally coiled strip having a trough depending inwardly from one lateral boundary thereof and a tongue depending inwardly from the other lateral boundary thereof for interlocking engagement with said trough of an adjacent turn of said helical strip.

4. A connector according to claim 1 wherein:

said first and second connecting means each include means for transmitting an electrical signal; and

said connector further includes an untensioned electrical conductor electrically interconnecting said first and second means and extending longitudinally through said flexible sheath.

5. A connector according to claim 4 wherein:

both said stretching means and said one of said first and second connecting means each include protruding therefrom a boss having said conductor extending therethrough and having a bore extending thereinto of a size for receiving an end of said flexible sheath;

the ends of said stretchable sheath are mechanically connected to said bosses; and

said flexible sheath is longitudinally slidable within at least one of said bores of said bosses.

6. A connector according to claim 5 wherein said rst connecting means comprises:

a breech cap having the other of said bosses protruding therefrom and formed for closing a breech of a pyrotechnic ejector assembly, said breech cap including a mechanical coupling member for connection to the ejector assembly and including primary contact means and ground contact means for applying a detonation signal to an electrically actuatable pyrotechnic cartridge.

7. A connector according to claim 6 wherein said second connecting means comprises:

a hollow anchor unit threadably engaging said adjusting member;

said conductor having a bend formed in a portion thereof extending within said housing for relieving tension in said conductor; and

a plug member electrically connected to said conductor and protruding from said anchor unit for establishing a mechanical and electrical connection with a signal source.

8. A connector according to claim wherein said stretching means comprises:

a iitting having one of said bosses protruding therefrom; and

an adjusting member formed for threadably engaging said fitting, said adjusting member including an oppositely threaded portion threadably engaged by said other of said rst and second connecting means.

9. A connector according to claim 1 further comprising:

said flexible sheath being formed to be more resistant to fiexure when subjected to radial compression; and

said adjustable stretching means being adjustable to cause stretchable sheath elongation of a sufficient degree enabling said stretchable sheath to radially compress said flexible sheath and reduce its ilexibility.

10. A connector according to claim 9 further comprising:

said adjustable stretching means including a turnbuckle having a conductor ensheathing bore extending therethrough and having one end connected to said stretchable sheath and the other end connected to said other of said rst and second connecting means; and

said connector further includes an untensioned electrical conductor extending through said ilexible sheath and said turnbuckle bore and electrically interconnecting said rst and second connecting means.

11. A connector comprising:

a ilexible sheath;

an untensioned electrical conductor extending longitudinally through said exible sheath;

a breech cap having a boss ,protruding therefrom which has said conductor extending therethrough and which has a bore extending thereinto of a size for receiving one end of said exible seath, said breech cap being formed for closing a breech of a pyrotechnic ejector assembly, said breech cap including a mechanical coupling member for connection to the ejector assembly and including primary contact means electrically connected to one end of said electrical conductor for applying a detonation signal to an electrically-actuatable pyrotechnic cartridge;

said breech cap further having ground contact means including a breech closing plate having an aperture and a tubular pin formed from a sheet of resilient electrically conductive material wound upon itself about an axis and arranged in said aperture to protrude from said plate, the protruding end thereof deining a plane oblique to said axis of said pin and being formed for piercing engagement of a cartridge casing;

a stretchable sheath having said tlexible sheath threaded therethrough and having one of its ends mechanically connected to said boss of said breech cap;

connecting means for transmitting an electrical signal electrically interconnected to the other end of said electrical conductor;

adjustable stretching means for mechanically interconnecting said stretchable sheath with said connecting means, said stretching means including protruding therefrom a boss Iwhich has said conductor extending therethrough and which is mechanically connected to the other end of said stretchable sheath, said boss having a bore extending thereinto of a size for receiving the other end of said exible sheath; and

said flexible sheath is longitudinally slidable Within at least one of said bores of said bosses.

12. A connector according to claim 11 wherein:

said pin includes an outer longitudinally extending edge of said material which has a length not longer than the average length of said pin.

13. A connector according to claim 12 wherein:

said pin includes an outer longitudinally extending edge of said lmaterial which has a length equal to the average length of said pin.

14. A connector comprising:

a flexible sheath;

an untensioned electrical conductor extending longitudinally through said exible sheath;

iirst and second connecting means each including means for passing an electrical signal and electrically interconnected by said conductor, one of said connecting means including protruding therefrom a boss which has said conductor extending therethrough and which has a bore extending thereinto of a size for receiving one end of said ilexible sheath;

a stretchable sheath having said ilexible sheath threaded therethrough and having one of its ends mechanically connected to said boss;

a fitting having a boss which has said conductor extending therethrough and which has the other end of said stretcable sheath mechanically connected thereto, said boss having a bore extending thereinto of a size for receiving the other end of said flexible sheath;

said flexible sheath being longitudinally slidable |within at least one of said bores of said bosses;

an adjusting member formed for threadably engaging said titting, said adjusting member including an oppositely-threaded portion threadably engaged by said other of said rst and second connecting means;

said tting, said adjusting member and said other of said rst and second connecting means each having slots formed therein which are registrable with one of those of each of the others; a key engageable with said slots in registration of said fitting, said adjusting means and said other connecting means for locking said adjusting members; and

means for retaining said key in said registered slots.

References Cited UNITED STATES PATENTS 2,028,793 l/l936 MaSCuCh 174-109 X 2,194,888 3/1940 Tramerye 174-106 X 2,865,978 12/1958 MOdrey 174-69 2,968,020 1/1961 Barnhart 339-30 3,251,216 5/1966 Broske 102-46 X SAMUEL W. ENGLE, Primary Examiner U.S. Cl. X.R. 

